title: Bioengineering of Leuconostoc mesenteroides glucansucrases that gives selected bond formation for glucan synthesis and/or acceptor-product synthesis.
abstract: The variations in glucosidic linkage specificity observed in products of different glucansucrases appear to be based on relatively small differences in amino acid sequences in their sugar-binding acceptor subsites. Various amino acid mutations near active sites of DSRBCB4 dextransucrase from Leuconostoc mesenteroides B-1299CB4 were constructed. A triple amino acid mutation (S642N/E643N/V644S) immediately next to the catalytic D641 (putative transition state stabilizing residue) converted DSRBCB4 enzyme from the synthesis of mainly α-(1→6) dextran to the synthesis of α-(1→6) glucan containing branches of α-(1→3) and α-(1→4) glucosidic linkages. The subsequent introduction of mutation V532P/V535I, located next to the catalytic D530 (nucleophile), resulted in the synthesis of an α-glucan containing increased branched α-(1→4) glucosidic linkages (approximately 11%). The results indicate that mutagenesis can guide glucansucrase toward the synthesis of various oligosaccharides or novel polysaccharides with completely altered linkages without compromising high transglycosylation activity and efficiency.
authors.affiliation: Research Institute for Catalysis and School of Biological Sciences and Technology, Chonnam National University, Gwang-Ju, Korea.
authors.forename: Hee Kyoung
authors.initials: HK
authors.lastname: Kang
authors.forename: Atsuo
authors.initials: A
authors.lastname: Kimura
authors.forename: Doman
authors.initials: D
authors.lastname: Kim
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D005936:Glucans / Q000096:biosynthesis*; D007934:Leuconostoc / Q000201:enzymology* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D015202:Protein Engineering; D013393:Sucrase / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D005936:Glucans; D013393:Sucrase